Word templates are files with extensions like .dot, .dotx or .dotm. These file types should not be used as mailmerge main document(s) as you're liable to get two SQL prompts, amongst other things.
You should only use files with extensions like .doc, .docx or .docm as your mailmerge main document(s). Then, when you click on 'Edit Individual Documents', Word will create a single new document containing all of the output for all of the records processed.
Regardless of whether your documents referenced by the INCLUDETEXT fields contain their own mergefields, these documents should not be connected to the datasource, as that's both unnecessary and is liable to generate additional SQL prompts.